Simple Module TCPEchoApp

Package: inet.applications.tcpapp
File: src/applications/tcpapp/TCPEchoApp.ned

Accepts any number of incoming TCP connections, and sends back the messages that arrive on them, The lengths of the messages are multiplied by echoFactor before sending them back (echoFactor=1 will result in sending back the same message unmodified.) The reply can also be delayed by a constant time (echoDelay parameter).

When TCPEchoApp receives data packets from TCP (and such, when they can be echoed) depends on the sendQueue/receiveQueue setting of TCP. With TCPVirtualBytesSendQueue/RcvQueue, TCP passes up data to us as soon as a segment arrives, so it can be echoed immediately. With TCPMsgBasedSendQueue/RcvQueue, our local TCP reproduces the same messages that the sender app passed down to its TCP -- so if the sender app sent a single 100 MB message, it will be echoed only when all 100 megabytes have arrived.

Compatible with both IPv4 and IPv6.

Usage diagram:

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Inheritance diagram:

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Parameters:

Name	Type	Default value	Description
address	string	""	local address; may be left empty ("")
port	int		port number to listen on
echoFactor	double	1
echoDelay	double	0s

Properties:

Name	Value	Description
display	i=block/app

Gates:

Name	Direction	Size	Description
tcpIn	input
tcpOut	output

Source code:

//
// Accepts any number of incoming TCP connections, and sends back the
// messages that arrive on them, The lengths of the messages are
// multiplied by echoFactor before sending them back (echoFactor=1 will
// result in sending back the same message unmodified.) The reply can also be
// delayed by a constant time (echoDelay parameter).
//
// When TCPEchoApp receives data packets from TCP (and such, when they can be
// echoed) depends on the sendQueue/receiveQueue setting of TCP.
// With TCPVirtualBytesSendQueue/RcvQueue, TCP passes up data to us
// as soon as a segment arrives, so it can be echoed immediately.
// With TCPMsgBasedSendQueue/RcvQueue, our local TCP reproduces the same
// messages that the sender app passed down to its TCP -- so if the sender
// app sent a single 100 MB message, it will be echoed only when all
// 100 megabytes have arrived.
//
// Compatible with both IPv4 and IPv6.
//
simple TCPEchoApp like TCPApp
{
    parameters:
        string address = default(""); // local address; may be left empty ("")
        int port; // port number to listen on
        double echoFactor = default(1);
        double echoDelay @unit("s") = default(0s);
        @display("i=block/app");
    gates:
        input tcpIn @labels(TCPCommand/up);
        output tcpOut @labels(TCPCommand/down);
}